Prince Harry, Duke of Sussex and Meghan, Duchess of Sussex arrive at Edes House in Chichester during an official visit to Sussex on October 3, 2018 in Sussex, United Kingdom. The Duke and Duchess married on May 19th 2018 in Windsor and were conferred The Duke & Duchess of Sussex by The Queen. (Photo by Samir Hussein/Samir Hussein/WireImage)

Siobhan told RSVP Live: "Meghan got pregnant straight away when she got married, so it is definitely a honeymoon baby.

"She is actually more than three months gone, she is about four months gone."

The baby news continues as the royal pair will welcome their second child soon after giving birth to baby number one.

"They will have another baby straight away, she will have two children in a row, so this time next year she will be pregnant again.